universalisos/docs/T10_POSIX_TASK_MANAGEMENT.md

T10: POSIX Task Management

Track: T10
Status: IN PROGRESS
Date: 2026-07-12
Source: UniversalisOS 12-Month Roadmap, Month 10

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Overview

T10 focuses on providing robust POSIX-like process semantics for UniversalisOS. This includes implementing task_fork, task_waitpid, halt partition logic, and proper POSIX subsystem initialization.

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Objectives

1. Implement task_fork — Create child tasks with proper memory isolation
2. Implement task_waitpid — Wait for child task completion
3. Implement halt partition logic — Graceful partition shutdown
4. Initialize POSIX subsystems — Proper posix_config.c initialization
5. Address POSIX ABI memory management — Complete mm.h declarations

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Tasks

T10-1: task_fork Implementation

Status: PENDING

Implement POSIX fork() semantics for UniversalisOS tasks:

/* Fork a new task */
pid_t task_fork(void);

/* Child task gets copy of parent's address space */
/* Parent task continues execution */
/* Both tasks return from fork() with different values */

Key Features:

• Copy-on-write (COW) memory semantics
• Independent address spaces
• Shared file descriptors
• Signal handling inheritance

TODO:

• Implement COW page tables
• Implement task state copying
• Implement return value handling
• Add fork() to POSIX ABI

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T10-2: task_waitpid Implementation

Status: PENDING

Implement POSIX waitpid() semantics:

/* Wait for child task to change state */
pid_t task_waitpid(pid_t pid, int* status, int options);

/* Options: WNOHANG, WUNTRACED, WCONTINUED */
/* Status: exit code, signal, stop/continue */

Key Features:

• Wait for specific child or any child
• Non-blocking option (WNOHANG)
• Status reporting (exit, signal, stop)
• Zombie task cleanup

TODO:

• Implement task state tracking
• Implement wait queue
• Implement status reporting
• Add waitpid() to POSIX ABI

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T10-3: Halt Partition Logic

Status: PENDING

Implement graceful partition shutdown:

/* Halt a partition */
int partition_halt(uint32_t partition_id);

/* Steps: */
/* 1. Stop all tasks in partition */
/* 2. Free all resources */
/* 3. Clean up memory */
/* 4. Notify hypervisor */

Key Features:

• Graceful task termination
• Resource cleanup
• Memory deallocation
• Hypervisor notification

TODO:

• Implement task termination
• Implement resource cleanup
• Implement memory deallocation
• Add halt to partition API

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T10-4: POSIX Subsystem Initialization

Status: PENDING

Initialize POSIX subsystems properly:

/* Initialize POSIX subsystems */
int posix_subsystem_init(void);

/* Subsystems: */
/* - File descriptors */
/* - Signals */
/* - Timers */
/* - Message queues */
/* - Shared memory */

Key Features:

• File descriptor table
• Signal handlers
• Timer management
• IPC initialization

TODO:

• Implement fd table initialization
• Implement signal handler setup
• Implement timer initialization
• Implement IPC initialization

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T10-5: POSIX ABI Memory Management

Status: PENDING

Complete POSIX ABI memory management declarations:

/* Already declared in mm.h (T8-2.1): */
/* - mm_mmap_guard */
/* - mm_mmap_aligned */
/* - mm_mremap_ex */
/* - mm_quarantine */
/* - mm_set_map_count */
/* - mm_set_accountable_limit */

/* Additional declarations needed: */
/* - mm_brk */
/* - mm_sbrk */
/* - mm_mlock */
/* - mm_munlock */
/* - mm_mlockall */
/* - mm_munlockall */

TODO:

• Add mm_brk declaration
• Add mm_sbrk declaration
• Add mm_mlock declarations
• Implement memory locking

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Implementation Files

File	Purpose
kernel/src/core/abi/uos_posix_abi.cpp	POSIX ABI implementation
kernel/src/core/abi/uos_posix_abi.h	POSIX ABI header
kernel/src/core/task.h	Task management
kernel/src/core/task.cpp	Task implementation
kernel/src/core/mm.h	Memory management
kernel/src/core/mm.cpp	Memory implementation

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Verification

• task_fork works correctly
• task_waitpid works correctly
• Halt partition works correctly
• POSIX subsystems initialize correctly
• Memory management declarations complete

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TODO Summary

T10-1: task_fork

• Implement COW page tables
• Implement task state copying
• Implement return value handling
• Add fork() to POSIX ABI

T10-2: task_waitpid

• Implement task state tracking
• Implement wait queue
• Implement status reporting
• Add waitpid() to POSIX ABI

T10-3: Halt Partition

• Implement task termination
• Implement resource cleanup
• Implement memory deallocation
• Add halt to partition API

T10-4: POSIX Subsystem Init

• Implement fd table initialization
• Implement signal handler setup
• Implement timer initialization
• Implement IPC initialization

T10-5: POSIX ABI MM

• Add mm_brk declaration
• Add mm_sbrk declaration
• Add mm_mlock declarations
• Implement memory locking

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References

• universalisos/docs/UniversalisOS_Stubs_Resolution_Roadmap_12Months.md — 12-month roadmap
• universalisos/kernel/src/core/abi/uos_posix_abi.cpp — POSIX ABI implementation
• universalisos/kernel/src/core/mm.h — Memory management declarations